• International conference on construction engineering and project management
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• 2022.06a
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• pp.361-369
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• 2022

Unsafe actions and behaviors of workers cause most accidents at construction sites. Nowadays, occupational safety is a top priority at construction sites. However, this problem often requires money and effort from investors or construction owners. Therefore, decreasing the accidents rates of workers and saving monitoring costs for contractors is necessary at construction sites. This study proposes an unsafe behavior detection method based on a skeleton model to classify three common unsafe behaviors on the scaffold: climbing, jumping, and running. First, the OpenPose method is used to obtain the workers' key points. Second, all skeleton datasets are aggregated from the temporary size. Third, the key point dataset becomes the input of the action classification model. The method is effective, with an accuracy rate of 89.6% precision and 90.5% recall of unsafe actions correctly detected in the experiment.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.808-813
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• 2022

This study presents the problems of data imbalance, varying difficulties across target objects, and small objects in construction object segmentation for far-field monitoring and utilize compound loss functions to address it. Construction site scenes of assembling scaffolds were analyzed to test the effectiveness of compound loss functions for five construction object classes---workers, hardhats, harnesses, straps, hooks. The challenging problem was mitigated by employing a focal and Jaccard loss terms in the original loss function of LinkNet segmentation model. The findings indicates the importance of the loss function design for model performance on construction site scenes for far-field monitoring.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.183-184
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• 2021

Defects such as falling and cracking of tiles installed in the bathrooms of apartment houses are frequently occurring. Therefore, in order to solve this problem, the A/S cost of construction companies and consumer complaints are increasing. The causes of tile defects include problems such as the selection of tile adhesive and lack of adhesive strength, the carelessness of the installer, the base surface, and the absorption rate of the tile. Therefore, in this study, an adhesive construction method using tile adhesives with high resistance to deformation of floors and tiles was studied. In addition, the properties and construction methods of tile adhesives were evaluated.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.230-231
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• 2021

In this study, Dr. Bae Kyu-woong of the Korea Institute of Construction Technology developed a concrete module that was lightweighted to 1700kN with KC modules and met housing performance standards. It solves Construction lifts problem that was the limit of the PC module, and is an innovative model that greatly improves Construction period and economics with boxed modules, and is manufactured in the factory by extruded molding in vibration, noise, fireproofing standards, etc., and has the advantage of excellent precision and high strength. Therefore, if the framing house of a precast concretecan only be standardized in construction, its potential for growth will be endless. To do this, standardization, standardization, and modularization of the design are essential.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.19-20
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• 2022

Based on the survey analysis of safety accidents at construction sites that occur every year, most of them are caused by temporary structures. While analyzing in detail, it is confirmed that the main factors for such accidents are the quality problem of temporary equipment, unstable construction, and arbitrary change. As temporary structure is installed only for the construction of main structure, the reality is that no attention is paid to the construction of temporary structures.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.99-103
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• 2003

The most commonly used method for space management in the industry is development of site plans. These plans outline how to manage material deliveries, staging areas, and crane locations for construction sites in suburban area but not in congested urban areas. This study focuses on how to efficiently manage space for construction facilities on high-rise buildings in congested urban areas where normally space for facilities around a building footprint is not available. The limitations of available horizontal space create a need to explore vertical expansion of facilities. This raises new aspects of vertical facility handling and flow that need to be considered in the facility design problem. The construction facilities layout plan method provides layout planners with a valuable technique to develop efficient sequences of work that optimally defines how to efficiently utilize the construction facilities and minimize the travel of specific facilities effort on multiple-floor buildings. A genetic algorithm-based heuristic will be presented for generating block layouts for multiple-floor la)rout problems.

• Computers and Concrete
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• v.18 no.5
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• pp.1041-1051
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• 2016

In this study, the construction of a reinforced concrete bridge pier was analyzed from durability point of view. The goal of the study is to analyze the crack iniation condition due to construction and present some recommendations for construction conditions of the reinforced concrete bridge pier. The bridge is located at the western port area of Shenzhen, where the climate is high temperature and humidity. To control the cracking of concrete, a construction simulation was carried out for a heat transfer problem as well as a thermal stress problem. A shrinkage model for heat produced due to cement hydration and a Burger constitutive model to simulate the creep effect are used. The modelling based on Femmasse(C) is verified by comparing with the testing results of a real underground abutment. For the bridge pier, the temperature and stress distribution, as well as their evolution with time are shown. To simulate the construction condition, four initial concrete temperatures ($5^{\circ}C$, $10^{\circ}C$, $15^{\circ}C$, $20^{\circ}C$) and three demoulding time tips (48h, 72h, 96h) are investigated. From the results, it is concluded that a high initial concrete temperature could result in a high extreme internal temperature, which causes the early peak temperature and the larger principle stresses. The demoulding time seems to be less important for the chosen study cases. Currently used 72 hours in the construction practice may be a reasonable choice.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.1
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• pp.195-200
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• 2017

Due to the rapid development of Internet technology, qualities of Web services are steadily improving and the Web database systems are actively employed to efficiently manage proper informations in various fields. In this paper, we propose a Web database system for the efficient material management for reusing construction materials. The proposed Web-based management system is operated using the spring framework, after constructing a database based on the collected data including tag ID, Location, Material, State, and Cycle, using the RFID(: Radion Frequency IDentification) system equipped with a location estimation module. Recently, the processing problem for a large amount of the residues generated at the demolition stage of various buildings is magnified in the construction site. The proposed Web-based construction material management system is expected for improving the processing problem as increasing the reusability and for reducing the construction cost as efficiently managing the construction materials for the reuse.

• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.479-488
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• 2018

The issue of waste and its recycling is perceived as a worldwide environmental problem, and the plastic waste is perceived as the biggest social problem threatening the lives of mankind. The vertical protective net, manufactured by using the plastic resin is vertically installed on the outside in case of formwork at the construction site, in order to prevent the fallen objects and scattered dusts. The objective of this study is to understand the actual use status of vertical protective net in the construction site, to examine the changes in the environment-related regulations recently strengthened in the construction site, and also to improve the field technicians' perception of it. And based on it, this study aims to suggest the measures for using the rational and environment-friendly materials and also for promoting the recycling of vertical protective net as the vertical protective nets made of plastic resin are thoughtlessly used in the construction site.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9B
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• pp.569-576
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• 2007

This paper is on the enhancement of our heuristics for GOSST problem that could apply to the design of communication networks offering graduated services. This problem hewn as one of NP-Hard problems finds a network topology meeting the G-Condition with minimum construction cost. In our prior research, we proposed two heuristics. We suggest methods of selecting G-Node and disconnections for Global or Local locating heuristic in this research. The ameliorated Local locating heuristic retrenches 17% more network construction cost saving ratio and the reformed Global locating heuristic does 14% more than our primitives.